diff options
| author | Alexander Duyck <alexander.h.duyck@intel.com> | 2013-03-22 15:04:48 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-03-22 16:41:20 -0700 |
| commit | 8d640a51ec9e9cdefa680b67ad55f933eefc5923 (patch) | |
| tree | c8e8964a54f42a529fceb6ef80590592d13bf68d /lib | |
| parent | 0ef1594c017521ea89278e80fe3f80dafb17abde (diff) | |
| download | lwn-8d640a51ec9e9cdefa680b67ad55f933eefc5923.tar.gz lwn-8d640a51ec9e9cdefa680b67ad55f933eefc5923.zip | |
dma-debug: fix locking bug in check_unmap()
In check_unmap() it is possible to get into a dead-locked state if
dma_mapping_error is called. The problem is that the bucket is locked in
check_unmap, and locked again by debug_dma_mapping_error which is called
by dma_mapping_error. To resolve that we must release the lock on the
bucket before making the call to dma_mapping_error.
[akpm@linux-foundation.org: restore 80-col trickery to be consistent with the rest of the file]
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Reviewed-by: Shuah Khan <shuah.khan@hp.com>
Tested-by: Shuah Khan <shuah.khan@hp.com>
Cc: Jakub Kicinski <kubakici@wp.pl>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/dma-debug.c | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/lib/dma-debug.c b/lib/dma-debug.c index 5e396accd3d0..d3e06a5e981e 100644 --- a/lib/dma-debug.c +++ b/lib/dma-debug.c @@ -862,17 +862,21 @@ static void check_unmap(struct dma_debug_entry *ref) entry = bucket_find_exact(bucket, ref); if (!entry) { + /* must drop lock before calling dma_mapping_error */ + put_hash_bucket(bucket, &flags); + if (dma_mapping_error(ref->dev, ref->dev_addr)) { err_printk(ref->dev, NULL, - "DMA-API: device driver tries " - "to free an invalid DMA memory address\n"); - return; + "DMA-API: device driver tries to free an " + "invalid DMA memory address\n"); + } else { + err_printk(ref->dev, NULL, + "DMA-API: device driver tries to free DMA " + "memory it has not allocated [device " + "address=0x%016llx] [size=%llu bytes]\n", + ref->dev_addr, ref->size); } - err_printk(ref->dev, NULL, "DMA-API: device driver tries " - "to free DMA memory it has not allocated " - "[device address=0x%016llx] [size=%llu bytes]\n", - ref->dev_addr, ref->size); - goto out; + return; } if (ref->size != entry->size) { @@ -936,7 +940,6 @@ static void check_unmap(struct dma_debug_entry *ref) hash_bucket_del(entry); dma_entry_free(entry); -out: put_hash_bucket(bucket, &flags); } |